The invention relates to an air-conditioning system, in particular an air-conditioning system for the air-conditioning of a passenger cabin of an airplane in accordance with the description herein. The invention further relates to a method for the preparation of air for the air-conditioning of a space, in particular for the air-conditioning of a passenger cabin of an airplane.
Air-conditioning systems for airplanes are known in numerous different embodiments. They in particular serve the heating and the cooling of the cabin, the cabin pressurization and the supply of fresh air. What is important is that the air-conditioning system has a construction size and a weight which are as low as possible, which is in particular of great interest in aircraft construction. Already known air-conditioning systems as a rule have a shaft device which includes a compressor and a turbine and which can additionally be provided with a blower arranged in a stagnation air passage. In already known systems, one or more heat exchangers are located in the stagnation air passage and serve to cool compressed air tapped from the engines or from auxiliary units. In already known systems, the compressed air is first cooled in a first heat exchanger in the stagnation air passage, is them compressed in the compressor of the shaft device, is cooled again in a second heat exchanger arranged in the stagnation air passage and is then supplied to a water extractor circuit. The air which has been dehumidified in this manner subsequently flows through the turbine of the shaft device and is then supplied to a mixing chamber or to the passenger cabin.
Air-conditioning systems are known in which two of the said systems are provided for reasons of redundancy. Embodiments are furthermore known in which not all components are present in two-fold form, but only those which have a comparatively high selection probability. Such an air-conditioning system in which the shaft devices are present in two-fold form, but the stagnation air heat exchanger and the water extractor circuit only in single form, is known from EP 0 891 279 B1.
A further development of the system known from this printed specification is the subject of DE 102 01 426. The air-conditioning system disclosed in this specification has at least one heat exchanger arranged in a stagnation air passage for the cooling of compressed air. The heat exchanger includes at least one first heat exchange unit and one second heat exchanger unit separate therefrom on the compressed air side of which a respective one is in communication with a respective one of the shaft devices on the compressed air side. The shaft devices have compressors which are in communication on the outlet side with the inlet on the compressed air side of the separate heat exchanger units on the compressed air side. The heat exchanger units each have their own compressed air supply.
A common stagnation air inlet passage and stagnation air outlet passages separate from one another in a mechanical flow aspect are provided for the at least two heat exchanger units.
A particularly compact and simultaneously reliable, redundant and cost-favorable arrangement is achieved by the air-conditioning system disclosed in DE 102 01 426 A1.
In the previously described air-conditioning system, the compressed air supplied to the system is taken from the engines. The tapping of the fresh air to be treated directly from the engine is, however, problematic to the extent that as a rule, an unwanted reduction in engine power is associated with the tapping of the air from the engine.